Adding the '--quiet' argument to gnome.generate_gir() silences
informational build output such as what g-ir-scanner was called with.
Gtk and others do this, so why don't we as well?
# UPDATING VERSION NUMBERS FOR RELEASES
#
# The version number is:
# <major>.<minor>.<micro><suffix>
#
# If any code has changed in libgnt:
# micro += 1
#
# If any functions have been added to libgnt:
# micro = 0
# minor += 1
#
# If backwards compatibility has been broken in libgnt:
# micro = 0
# minor = 0
# major += 1
# gnt_soversion += 1
#
# suffix should be similar to one of the following: